Open Stack

Just a heads-up that the 3.10 kernel in CentOS/RHEL is *not* a stock 3.10 
kernel.  It has had many things backported from later kernels, though they may 
not have backported the specific improvements you're looking for.

I think CentOS is using qemu 2.3, which is pretty new.  Not sure how new their 
libiscsi is though.

Chris

On 03/07/2016 12:25 AM, Preston L. Bannister wrote:
> Should add that the physical host of the moment is Centos 7 with a packstack
> install of OpenStack. The instance is Ubuntu Trusty. Centos 7 has a relatively
> old 3.10 Linux kernel.
>
>  From the last week (or so) of digging, I found there were substantial claimed
> improvements in /both/ flash support in Linux and the block I/O path in QEMU -
> in more recent versions. How much that impacts the current measures, I do not
> (yet) know.
>
> Which suggests a bit of tension. Redhat folk are behind much of these
> improvements, but RHEL (and Centos) are rather far behind. Existing RHEL
> customers want and need careful, conservative changes. Folk deploying OpenStack
> need more aggressive release content, for which Ubuntu is currently the best base.
>
> Will we see a "Redhat Cloud Base" as an offering with RHEL support levels, and
> more aggressive QEMU and Linux kernel inclusion?
>
> At least for now, building OpenStack clouds on Ubuntu might be a much better bet.
>
>
> Are those claimed improvements in QEMU and the Linux kernel going to make a
> difference in my measured result? I do not know. Still reading, building tests,
> and collecting measures...
>
>
>
>
> On Thu, Mar 3, 2016 at 11:28 AM, Chris Friesen <chris.friesen at windriver.com
> <mailto:chris.friesen at windriver.com>> wrote:
>
>     On 03/03/2016 01:13 PM, Preston L. Bannister wrote:
>
>              > Scanning the same volume from within the instance still gets the same
>              > ~450MB/s that I saw before.
>
>              Hmmm, with iSCSI inbetween that could be the TCP memcpy limitation.
>
>
>         Measuring iSCSI in isolation is next on my list. Both on the physical
>         host, and
>         in the instance. (Now to find that link to the iSCSI test, again...)
>
>
>     Based on earlier comments it appears that you're using the qemu built-in
>     iSCSI initiator.
>
>     Assuming that's the case, maybe it would make sense to do a test run with
>     the in-kernel iSCSI code and take qemu out of the picture?
>
>     Chris
>
>
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